Fuel injection device



Sheets-Sheet l Filed Oct. 2, 1946 Mmmuayv Sept.- 14, 1948. R. HUBER FUEL INJECTION DEVICE 2 Sheets-Sheet 2 Filed Oct. 2. 1946 INVENTOR Patented Sept. i4, 1948 FUEL NJ ECTION DEWCE Robert Huber, Paris, France, assigner of ninetenths to Raul Pateras Pescara, Paris, France, and one-tenth 'to Societe dliitudes et de Farticipations, Eau, Gau, Electricite, Energie, S. A., Geneva, Switzerland, a society oi Switzerland Application @ctober 2, 19416, Serial No. fiilfil lin France ctober22, i945 (Cl. S-+37) 4 Claims.

The present invention relates to fuel injection `device oi this type which is better adapted to meet the requirements of practice than those used for the same purpose up to the present time.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely 'by way o example, and in which:

Fig. l is an axial sectional view of a fuel in jection device made according to a first embodiment of my invention;

Fig. 2 is a similar view oia device of the same kind made according to another embodiment;

In the following descrlption,it will be ,l supposed that the invention is applied to the case `cfa fuel injection device for an internal combustion engine, for instance an engine belonging to. alfree piston machine.

`The injection pump may be of any suitable construction. For instance, according to a conventional arrangement, it includes a piston I adapted to be rotated about its axis for adjustment of the amount of fuel fed on every stroke, this piston being provided with a cam-like surface 2v serving to determine, according to the angular position of piston I about its axis, either ,the end (Fig. 1) or the beginning (Fig. 2) of the fuel delivery by opening or closing, respecutively, the communication between the inside of the pump cylinder 3 and the inlet port I of this cylinder.

The axial reciprocating movement of piston is nsured through any suitable means, for intance a cam (not shown by the drawings).

t" lMeans are provided for forming, for instance immediately above cylinder head 5, an accumulator chamber 6 adapted to coact with an accumulator piston 'I movable inside a sleeve 8 in line with accumulator chamber 6. This piston 1 is subjected to the action of a suitable force. for instance that exerted by a spring 1a which urges said piston toward the inside of chamber 6 so as to tend to reduce the volume thereof.

The communication between cylinder t and accumulator chamber d is controlled, in the embodiment of Fig. l, by a valve t subjected to the action oi spring 9a, or otherwise, as in the case of the embodiment of Fig. 2, by the action of special means which will be hereinafter described.

In order to prevent the possibility of too high pressures being developed in chamber t, I may fit the latter with a safety valve such as Id which opens, against the action of a spring il, when the pressure in chamber E exceeds a predetermined value.

The means for controlling the communication between accun'iulator` chamber t and conduit I2, which leads to the fuel injector, include a valve which, according to my invention, is operative in response to movements of piston I, so ,as to open, in particular, when this piston is close to the end of its inwardstroke.

For this purpose, I may either cause piston i.v

or a part movable therewith, to act directly on said communication controlling valve, or have this valve operated by the pressure of a fluid subjected to the action of said piston or said part movable therewith, this fluid preferably consisting of the fuel delivered by the piston.

Fig. l shows an example of the iirst of these embodiments. The communication controlling valve in question, shown at I3 and subjected to the action of a spring 93a that urges it toward its closed position, has a stem provided with a groove lli located opposite the inlet of a passage I in communication with conduit I2. This stem of valve i3 extends downwardly so as to project into cylinder 3. Thus, piston I, at theend of its inward stroke, comes into contact with the end of said valve stem and pushes it so as to lift valve i3 from its seat. Accumulator chamber 6 is then brought into communication with conduit I2 through groove I4 and passage I5. A portion of the fuel present in chamber 6 and subjected to the pressure of accumulator piston l is injected into the engine cylinder by the injector fed through conduit I2.

Although valve I3 may be wholly independent of delivery valve 9, it is particularly advantageous to dispose valve 9 in an axial conduit I6 extending throughout valve I3.

In the embodiment of Fig. 2, the communication between accumulator chamber 6 and conduit I2 is also controlled by a valve I3 the stem of which is provided with a, groove Il'. As in the above described embodiment the end of-this valve stem projects into cylinder 3 and valve I3' is 2,44asea provided with an axial conduit IB'. But this last mentioned conduit is free from any closing means such as the delivery valve 9 of the preceding embodiment. On the other end the lower end of the stem of valve I3' is bevelled so that the end face of piston I, when applied against this valve stem end, closes conduit I6' in a iiuidtight manner.

In the embodiment of Fig. 2, the end of the delivery stroke must not vary. It takes place when the groove I8 of piston I, which is constantly in communication with the inside of cylinder` 3 through passage I9, comes opposite inlet port 4, whereas, owing to the provision of cam-like surface 2, the beginning of the delivery is variable, since delivery begins only when the edge 2 of piston I completely closes inlet port l. Furthermore, the distance a between the end face of piston I and the lower end of the stem of valve I3' when the piston is at the end of its outward stroke, must be smaller than the distance b between the upper edge of groove I8 and the lower edge of port I4 for the same position of the piston.

The device shown by Fig. 2 works in the following manner:

After inlet port l has been closed by piston I, y

the latter delivers fuel into accumulator chamber 6, this fuel being at a pressure corresponding to the strength of the spring 1a that acts on piston 1. During the beginning of this delivery stroke, valve I3 remains closed. However. when the end face of piston I gets close to the end of the stem of said valve, the liquid present in the annular space c of cylinder 3, i. e. between the lower end of said valve stem and the inner cylindrical wall of said cylinder, is subjected. due to the throttling of the communication between said annular space and conduit I6', to a pressure higher than that existing in chamber 6. This pressure difference 'causes valve I3' to lift from its seat without any metallic contact having taken place between the end face of piston I and the end of the valve stem. The layer of liquid present between these two parts .thus plays a shock absorbing action which preserves valve 'I3' against premature wear and y tear. Thisv pressure increase in annular space c ceases when the upper edge of groove I8 reaches the lower end of port 4 and the bevelled edge I1 i of the valve stem then comes into contact with the end face of piston I to close conduit I8 and present the fuel present in chamber 6 from flowing back into pump cylinder 3. However, the small movement necessary for applying the bevelled edge I1 of the valvestem against the end face of piston I is not suiiicient for closing valve I3'. On the contrary, the latter remains open until piston I is on its return stroke.

According to another feature of my invention, 'instead of causing spring 1a to act directly upon piston 1, this spring is adapted to act upon an intermediate piece, for instance a piston 20 as shown in the embodiment of Fig. 1 or a cap 2I as shown in the embodiment of Fig. 2, this piece being in contact with the head 1 of accumulator piston 1, which is applied against said piece by the pressure existing in accumulator chamber 6.

When the pressure in this chamber is low, spring 1a applies intermediate piece 20 or 2| against a fixed abutment. In the embodiment of`Fig. l, this abutment is for instance constituted by the upper part 22 of the pump body. In the embodiment of Fig. 2, it is constituted by an annular part 23 bearing on said pump body. Anyway, a certain play is left between the upper end of sleeve I and the head 1' of piston 1, so as to prevent :iol

-piston 1 fron being injured by shocks of said of easily varying the pressure in accumulator chamber 6 and consequently the injection pressure.

A conduit 21 is provided for evacuating air or fuel leaks. i The fuel injection device according to my invention has thejadvantage of being particularly simple and of occupying the minimum volume.

While I have, in the above description, disclosed what I deem to be practical and eillcient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement,

disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:'

l. A fuel injection device which comprises, in combination, means forming an accumulator chamber for fuel under pressure, a piston pump for feeding fuel to said chamber. a delivery conduit for leading fuel from said chamber to a fuel injector, a, valve adapted to control communication between said chamber and said conduit slidable in line with the pump piston and adapted to be pushed by it into opened position at the end of the inward stroke of said piston, and a check valve between said chamber and said pump.

' 2. A fuel injection device which comprises, in combination, means forming an accumulator chamber for fuel under pressure, a piston pump for-feeding fuel to said chamber, a delivery conduit for leading fuel from said chamber to a. fuel injector, a valve adapted to control communica tion between said chamber and said conduit slidable in line with the pump piston and adapted to b e pushed by it into opened position at the end of the inward stroke of said piston, and a check valve between said chamber and said pump mounted' coaxially inside said communication controlling valve.

3. A fuel injection device which comprises. in combination, means forming an accumulator chamber for fuel under pressure, avpump for feeding fuel to said chamber including a cylinder and a piston movable in said cylinder, means forming a passage coaxial with and of smaller diameter than said cylinder extending between said cylinder and said chamber, a delivery conduit for leading fuel from said chamber to a fuel injector, and a valve adapted to control communication between said chamber and said conduit including a tubular stem slidable in said passage and extending into said cylinder, the end of said stem located in said cylinder having a beveled edge. said valve stem being so dimensioned as to come into contact withsaid piston at'the end ofthe inward stroke thereof,

4. A fuel injectiondevice which comprisesfin combination, means forming an accumulator'4 chamber, an accumulator piston slidablevv in af portion of said chamber, elastic means for urging for intermittently connecting said chamber vvith 10 421,843

said conduit. y

ROBERT HUBER.

REFERENCES CITED The following references are of `record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,414,261 Kalitlnsky Jan. 14, 1947 2,414,267 Meitzler Jan. 14, 1947 2,420,431 Kalitinsky May 13, 1947 Meitzler June 10, 1947 

